1. Field of the Invention
The present invention relates to a subsea template and method for using the same and more particularly to such templates and methods in which a template is used on a sea floor to install one or more well casings.
2. Setting of the Invention
In the drilling of offshore wells it is common to install a template on the sea floor over the formation into which a well is to be drilled. The template typically comprises a frame made up of tubing having several passageways therethrough. The template is typically fixedly connected to piles which are driven into the sea floor in order to secure the template. References herein to the "sea" floor and to "subsea" templates and the like should be taken to include references to any body of water in which an underwater well may be drilled.
When so secured, the template provides a means for spacing the various wellbores which are to be drilled into the formation and also supports the well casing and loads from the drilling riser and blowout preventer stack as well as other environmental loads during drilling and production.
Numerous prior art templates are provided which include means for leveling the template relative to a nonlevel sea floor. This is desirable in order for the template to properly receive the piles, conductors, drillstring and various risers, all of which approach the sea floor from a platform or floating vessel in a substantially vertical orientation.
Leveling equipment and techniques for subsea templates have greatly increased the cost of the templates and often involve the use of underwater divers or remote operated vehicles to accomplish template leveling.
In some instances, a template may be installed on a substantially level sea floor and conductors, piles, drill bits and the like may approach the template in a substantially nonvertical orientation due to drillstring bending of to the position of the platform from which the drillstring is lowered. In some cases, it would be desirable to lower the drillstring or casing string through the template in a nonvertical orientation in order to drill or case a slightly angled wellbore. Prior art templates are constructed to receive conductors, piles, drillstrings and the like at an angle substantially perpendicular to the template.
There exists a need for a template and method for using the same in which the template may be anchored to a sea floor without the need for leveling the same.
There exists a need for such a template and method for using the same in which drillstrings, casing strings and the like may be received through a template installed on the sea floor at angles other than substantially perpendicular to the template.